This work summarizes the state of the art information related to scenarios and architectures from Energy-efficient High-speed Cost Effective Cooperative Backhaul for LTE/LTE-A Small-cells (E-COOP) technologies. One of the proposed architectures exploits infrastructure based on small cell deployment using RRU technology which is connected to the core network using backhaul technology based on fibre optic links. In E-COOP, we go beyond this by addressing four key scenarios in terms of fronthaul deployment strategy (scenario 1) for C-RAN and carrier aggregation (scenario 2). The third scenario exploits the C-RAN architecture to firstly split the control/ data plane where the macro base station improves the signalling service for the whole area. Also, mobile small cells (SCs) are cooperatively specialized towards delivering data services for high-rate transmission with light overhead control and appropriate air interface (mmWave) – scenario 3. This raises significant research challenges in terms of mobile small cell coexistence, and mobility management. In scenario 4, we consider SON in LTE-A for HetNets with ultra-dense small cell deployment with imperfect backhaul. A Primary Network is considered that is overlaid with a cognitive network of Small Cell Networks, performing local sensing and local self-configuration and -optimization algorithms.